<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width,initial-scale=1.0,user-scalable=no">
    <title>vue</title>
  </head>
  <body>
    <div id="app"></div>
  </body>
  <script>
    let htmlwidth = document.documentElement.clientWidth || document.body.clientWidth;
    let htmlDom = document.getElementsByTagName('html')[0];
    htmlDom.style.fontSize = htmlwidth/20 + "px";
  </script>
</html>
